Ethereum is a contract validating and enforcing system based on a distributed public ledger such as the one implemented by the Bitcoin cryptocurrency. The system allows for the management of complex distributed autonomous organizations, which raises questions about legality. Could this new platform promote the establishment of an entirely decentralized society, or will its disruptive potential eventually be absorbed by the established system? In this talk Primavera De Filippi — Berkman fellow and postdoctoral researcher at the CERSA/CNRS/Université Paris II — explores the dangers and opportunities of Ethereum.